Thread chain severing device for sewing machines



May 12., 1970 STRAUSS ETAL 3,511,202

THREAD CHAIN SEVERING DEVICE FOR SEWING MACHINES Filed Feb. 28, 1968 2 Sheets-Sheet 1 BRYANT THOM AS INVENTOR.

/ IRA STRAUSS May 12, 1970 l- STRAUSS E L 3,511,202

THREAD CHAIN SEVERING DEVICE FOR SEWING MACHINES Filed Feb. 28, 1968 2 Sheets-Sheet 3 IRA STRALIS$ BRYAN T THOM AS INVENTOR.

BY @QZN ATTOP YZ'Y United States Patent 3,511,202 THREAD CHAIN SEVERING DEVICE FOR SEWING MACHINES Ira Strauss, 72 Spring St., New York, N.Y. 10012, and I13ryant Thomas, 1225 Morris Ave., Bronx, N.Y.

Filed Feb. 28, 1968, Ser. No. 709,111 Int. Cl. Db 65/06 US. Cl. 112-252 5 Claims ABSTRACT OF THE DISCLOSURE The invention involves a thread chain cutting device for cutting and removing the chain formed between successive pieces of work fed through a sewing machine by utilization of a novel vacuum-operated tubular mem ber automatically effective and operational with the running of the sewing machine, said tubular member being so constructed and functional as to draw and cut the thread chain without the necessity for utilization of a thread chain feed dog.

This invention relates generally to a simplified construction for automatically severing and removing the thread chain by vacuum operation between successive work pieces fed through a sewing machine, and is an improvement over US. Pat. No. 3,143,987 granted to H. F. Daniel et al.

Prior attempts have been made to perform desired severing operation automatically through use of suction devices provided on sewing machines, but such devices have involved a complicated set-up and have failed effectively to guard against the edge of the material being drawn into the suction tube or toward the cutting device thereby interfering with economic and positive cutting operations of the thread.

As will be explained hereinafter, the cutting device which severs the thread chain is afforded by an external reciprocating knife blade cooperating with an edge in a slot of the vacuum tubular member, said tubular member also being of such construction as to ease passage of the stitched material.

A further feature of the invention is provision of a vacuum pump connected to the main motor and automatically operative with and during the running of the sewing machine, said pump being adapted to withdraw thread chain cuttings through a hose connection between an end of the vacuum tubular member and a storage container.

With the above objects and features of the invention in view, an embodiment of the invention will now be described in accordance with the accompanying drawings and the appended claims.

FIG. 1 is a view in perspective and partly diagrammatic, showing parts involved in the invention.

FIG. 2 is a plan view showing various elements in the construction shown in FIG. 1.

FIG. 3 is an elevational view of parts involved in the invention at the region of stitch formation of a sewing machine of the overage stitch forming type.

FIG. 4 is a fragmentary end view of the vacuum tubular member and the reciprocating knife blade of FIG. 3.

FIG. 5 is a fragmentary view in perspective of the tubular vacuum member also showing the cutting mechanism and the plane and direction of movement of the stitched chain edge of the work piece.

The drawings illustrate the invention in detail, and it is deemed unecessary to show the structure of the type of sewing machine to which the invention is applied. This invention is preferably applied to overedge sewing ice machine of the type as disclosed in US. patent to Wallenberg et al., 2,704,042 and granted Mar. 15, 1955.

In accordance with the invention and the embodiment shown, numeral 10 illustrates a work support, a throat plate 11 being provided adjacent the work support in the region of stitch formation. A conventional presser foot 12 is provided carried by a conventional spring arm (not shown) and which serves to retain the work to be stitched against the surface of the throat plate.

Adjacent presser foot 12 are provided suitable stitch forming devices for producing an overedge line of stitching, and includes a needle 13 and loopers or spreaders disposed beneath the throat plate 11 (not shown). In the course of the operation of the machine, the work is advanced by a plurality of feed dogs 14 and 15 which pass upwardly through suitable openings in the throat plate 11. A spaced stitch finger or tongue 16 is carried by throat plate 11 permitting needle 13 to enter the work piece 17 and secure the chain stitch 18 thereto. The loopers or spreaders above mentioned are adapted to be disposed below finger 16 and to cooperate with needle 13. Feed dogs 14 and 15 are driven by suitable connections from the main drive shaft of the machine as illustrated in the Wallenberg et al. patent.

As each work piece 17 is advanced through the stitch forming zone of the sewing machine and carried beyond tho latter, a thread chain 19 is formed that extends from the trailing end of the work piece 17 that has been stitched to the leading end of the next following work piece. This thread chain 19 is advanced toward the left (FIG. 2) by the suction action of a bore 20 in tubular member 21 in a plane slightly below the plane of said thread chain as will hereinafter appear.

Tubular member 21 as shown in FIG. 5 may be rectangular in cross-section. Member 21 has a forward vertical face 22 preferably provided with a rounded upper horizontal edge 23 and also has a top flat wall 24 disposed adjacent to, behind and slightly below the plane of stitch finger 16. The axis of bore 20 of tubular member 21 is disposed above that of said member 21 as shown in FIG. 5 so that as work piece 17 continues its uninterrupted advance to the left and passes along top wall 24 of said member 21, the trailing thread chain is suctionally pulled off the stitch finger 16 and is first drawn into the forward part of bore 20 as the lower of a double loop, the upper loop being in contact with rounded edge 23. As the work piece 17 passes beyond edge 23, the lower loop lengthens toward the rear of bore 20 and hydraulic action forces the upper loop to enter slot 25 along the upper left quadrant of the rounded edge of the face of bore 20. In the position shown in FIG. 5, the lower loop as extended is indicated at 19:: and the upper loop is in slot 25 for severance. To make this possible, face 22 of tubular member 21 and the vertical longitudinal wall 24a are provided with such a slot which extends laterally from said left quadrant of bore 20 and downwardly and obliquely a distance from intersecting edge of the walls 22 and 24 of the tubular member. Thus, slot 25 having a vertical dimension sufficient to enable the free passage of the thread chain 19 therethrough and therealong, cannot draw against the edge of work piece 17 thereabove.

Accordingly, when the work piece reaches the position indicated in FIG. 5, thread chain 19 will have a portion 19b extending inside bore 20. The other portion will be transverse to tubular member 21 passing outwardly through the slot 25 shown therealong to be at enlarged area 25a to the work piece 17. When the parts are in this position, the thread chain 19 will be automatically severed by the action of a reciprocating knife blade 26 mounted on member 27 with a cooperating cutter edge 25]) afforded by the upper forward edge on wall 24a of slot 25. Blade 26 3 may be operated through any suitable connection adapted to reciprocate the movable blade 26 upon each revolution of the drive shaft (such as one of the pitmans 126 and 128 shown in the Wallenberg et al. patent), said connection being adapted to run the rear feed dog 15.

Thus, whenever the trailing end of a work piece reaches the zone of action of blade 26 and cutter edge 25b, the transversely extending portion 19c of the thread chain will be neatly severed with a minimum of length of thread 190 attached to the work piece and issuing from slot 25. The remaining free thread after severance is unlooped in bore 20 and sucked back, becoming attaching to the leading end of the next work piece. When such leading end passes over wall 24, the adjacent portion of the thread chain extending into bore 20 will slide over rounded edge 23 and be drawn into slot 25 as described above for cutting position by cutters 26 and 25b to free the thread chain for delivery by the suction action to a disposal element to be described.

The coordination of sewing machine operation with vacuum operation is accomplished as diagrammatically shown in FIG. 1 wherein the main motor 28 for the machine operates a stitch-length control element 29, the cutting blade 26, the feed dogs 14 and and the suction means. Said suction means consists of the main motor 28, a vacuum pump 30, a mufiler 31 and a disposal element 32. Disposal element 32 is connected to bore of tubular member 21 by any suitable hose such as 33.

It is distinctly understood that other modifications or embodiments of thread chain cutting means alone and in coordination thereof with vacuum-producing structure may be made, within the spirit of the invention.

We claim:

1. In a sewing machine, means adapted to form a chain of thread between successive work pieces fed through the stitch forming mechanism of the machine including a stitch tongue, a member provided with a longitudinal bore of sufficient size to permit the chain of thread to pass therethrough, said member having a top wall disposed behind, below and adjacent to the stitch tongue and the chain of thread as the latter is formed by said chain forming means thereon, said work pieces being adapted to travel toward and along the top wall of said member, means for suction creation within the bore of said member and adapted to have the chains of thread formed between successive work pieces drawn into the bore from the inlet end of the member by suction directly from and off the stitch tongue of said chain forming means, said member having at the inlet end a passageway communicating with the bore and of a size to permit entrance and penetration to the end of the passageway of the chain of thread thereby enabling a portion of a thread chain attached to a work piece to enter and penetrate into said passageway, and thread severing means disposed below the top wall of said member and operable for severing the thread chain in the passageway at a point adjacent that at which the thread chain extends from the work piece disposed on the top wall of the member through the passageway as a result of the suction within said member.

2. In a sewing machine as set forth in claim 1 wherein a motor is connected to and adapted to operate the means adapted to form the chain of thread, the stitch forming mechanism and the thread severing means, a storage container connected to the member to receive the thread chain cuttings, and a vacuum pump connected to the storage cuttings, and a vacuum pump connected to the chronous operation with the sewing machine.

3. In a sewing machine as set forth in claim 1 wherein said member has a lateral front wall and an inlet end wall, said end wall having a narrow passageway communicating with the bore and extending downwardly and obliquely and along the front lateral wall for a limited distance thereby enabling a portion of the thread chain attached to a work piece to enter and penetrate into said passageway, and thread severing means operable externally of the member for severing the thread chain at a point adjacent that at which the thread chain extends from the work piece disposed on the top wall of the member through the passageway as a result of the suction within said member.

4. In a sewing machine as set forth in claim 3 wherein said thread severing means is comprised of a movable blade externally disposed relative to the member and a stationary blade afforded by the edges of the passageway along the lateral front wall of the tubular member.

5. In a sewing machine as set forth in claim 3 said sewing ma ching having a throat plate over which the work pieces are passed as they are being stitched, said passageway for the thread being a slit below the plane of the top of said throat plate.

References Cited UNITED STATES PATENTS 2,989,935 6/1961 Buttler ll2252 3,058,438 10/l962 Russell et al. l12252 3,143,987 8/1964 Daniel et a1. 112252 3,149,594 9/1964 BuckIeus et a1. 112-252 3,242,892 3/1966 Fowler 112252 JAMES R. BOLER, Primary Examiner 

